The invention relates to medicine, namely to the antimicrobial agent for the treatment of infectious bacterial diseases including hospital infections and drug-resistant TB which represents the ion nanostructured complex (INSC) synthesized from carbohydrates proteins and/or polypeptides (albumins, interleukins, interferons, signaling proteins, etc), which are to enhance the antimicrobial activity in vivo, by activating immune cells that contain at least one terminal amino acid such as Phe, Ala, Val, Ala, Leu, Ile, and others with electron-donor functional groups, iodine and halides of the alkali and alkaline earth elements in the fourth stage at a certain ionic strength; an antibacterial agent increases : the susceptibility of bacteria, including antibiotic-resistant, to antibiotics; activity of monocytes and macrophages; efficiency of antibiotic treatment of hospital infections and drug-resistant TB; it also has antiviral activity, stimulates hematopoietic function of bone marrow; has an antitumor effect and radioprotective properties; in acceptable concentrations of components can be used as non-pharmaceutical agent (BAFS or parapharmaceutical); is presented in the pharmacological form suitable for parenteral, oral, external, or other application. INSC has the formula [{(Ln (MeI3)+) y [Me (Lm) I]+x} (Cl—) y+x+k] with M=30-300 kDa.